forming the Nile-Rudolf watershed, which drops abruptly into the Turkana plain on the Rudolf side, but slopes gradually westwards to the Nile. It has heights of 10,000 feet. The expeditions named nearly completed the exploration of the region between the Nile and Abyssinia. In 19156 Maj. Cuthbert Christy made a ten months' journey along the Congo-Nile divide, where it forms the frontier of the Anglo-Egyptian Sudan. The divide proved to be " a continu- ous and more or jess level strip of bush-covered country (mostly of ironstone formation), sometimes as much as two miles in width but often only a few yards." In Maj. Christy's opinion the divide was perfectly suitable for the building of a railway, a roundabout link in the Cape-to-Cairo scheme.
Mr. I. N. Dracopoli in 1912-3 explored part of southern Jubaland. He reached the Lorian Swamp which receives the waters of the Uaso Nyiro and solved the problem of its outflow. He found that the Lake Dera issues from Lorian in a well-defined bed and, though usually dry in its lower course, is, through Lake Wama, a tributary of the Juba river. Mr. (afterwards Sir) G. F. Archer completed in April 1912, after over two years' work, surveys connecting the triangulation of British East Africa with Maj. Gwynn's Abyssinian boundary survey. Captain R. E. Salkeld in 1913-4 further explored Jubaland, drawing attention to the over- running of that region by the Somalis the most recent instance of the migration of African races.
In east central Africa a survey by Capt. E. M. Jack, in 1911. of the region N.E. of Lake Kivu and W. of Victoria Nyanza resulted in making known a healthy highland region and added to the knowl- edge of the Mfumbiro range of active volcanoes. Karissimbi was found to be 14,780 ft. high. In Dec. 1912 Sir A. Sharpe and Mr. M. Elphinstone witnessed the formation of a new volcano, named Katarusi, which, following an earthquake, rose out of an old grass-covered lava-field, sending into the N.E. corner of Kivu a river of lava which filled up a " large bay."
The first survey along its whole length of the Congo-Zambezi watershed was made in 1911-4 by Anglo-Belgian and Anglo- Portuguese boundary commissions, the principal commissioners being Capt. Everest (killed by a lion), Maj. E. A. Steel and Mai. Reginald Walker (British), Maj. Begraud and Capt. Web- er (Belgian) and Capts. C. V. Cago Coutinho and V. da Rocha (Portuguese). As in the Congo-Nile watershed, it was found that many rivers ran for considerable distances parallel to the divide, which is largely bush-covered. Major Walker discovered that the Luapula (the main eastern headstream of the Congo) did not, as was believed, issue from Lake Bangweulu, but was a continuation of the Chambezi, which passes through the great swamp S. of Bangweulu.
Another boundary commission, under Capt. W. V. Nugent and Oberleutnant Detzner, in 1912-3 demarcated the Nigeria- Cameroon frontier between Yola and the Cross river. The frontier followed roughly the edge of the highlands overlooking the fertile plains of the Benue and was an instance where the straight lines drawn on the map by diplomatists to mark international boundaries worked out fairly well in practice.
During the World War exigencies of campaigning led to many additions to exact knowledge of the topography of tropical Africa, partly through the use of aircraft for survey purposes. Thus very useful maps, showing routes unsuspected on the ground, were made of Portuguese Nyasaland by airmen. In 1920 Dr. P. Chalmers Mitchell, who passed over the whole length of the Nile basin in an aeroplane, proved the value to geology of air reconnaissances by the discovery in the Bayuda desert N. of Khartoum, of the volcanic character of a range of hills. Between Old Merowe and Atbara the aeroplane crossed " a high and irregular range of hills running east and west. In the middle of them was a great plain looking like toffee poured out on a plate. From this a number of craters rose, two large, one with a sandy interior with thorn bushes, the other with a second peak and crater inside the outer rim." From pieces of tufa recently obtained from the Nile Valley, N. of Khartoum, the existence of some unknown Tertiary volcanic field in that region had been sus- pected. Exploration on the ground remained to be undertaken, but Dr. Chalmers Mitchell's observations would appear to be the first important geological discovery made from the air.
2. Communications. The first railway and steamer route across Africa was completed by the opening in March 1915 of a railway from Kabalo on the Lualaba (Upper Congo) to Albertville on the west shores of Lake Tanganyika. The year before (1914) the Ger- man railway from Dar es Salaam had reached Kigoma, on the east shores of Tanganyika. A part of this Atlantic-Indian Ocean route is by the Congo, the non-navigable stretches of the river being bridged by railway. An all-rail east-west route across South Africa had also been effected in 1915, when a line was built from Prieska to Kalkfontein connecting the S.A. system with that of German South-West Africa. By this means Walfish Bay and Delagoa Bay were linked by railway. A second east-west all-rail route across Africa will be provided by the railway from Lobito Bay to Katanga, where it will join the lines to Beira and other east-coast ports, as well as to Cape Town. In 1920 some 600 m. of rails remained to be laid on this route. The surveys had been completed in 1920 and construction began in 1921.
None of these lines was designed as a transcontinental route,
though the Dar es Salaam-Congo route was so used for passenger traffic.
With the Cape-to-Cairo scheme little progress was made in the period 1910-21. The railway from Cape Town via Bulawayo and the Victoria Falls, which had reached the Belgian Congo frontier in 1009, was however continued N. across Katanga to Bukama on the Lualaba (Upper Congo), the line being completed in May 1918 an addition of 442 m. in ten years, making a through service from the Cape, on the same gauge (3 ft. 6 in.), of 2,598 miles. In 1921 the construction of a further section of the railway to a more north- erly point on the Lualaba. where navigation was easier than at Bukama, was begun. But from 1918 it was possible, by utilizing the Congo and Tanganyika systems, to travel alternately by train and steamer from the Cape to Cairo, with only two breaks together not more than 300 m. to be covered on foot. The southern break was from Tabora (on the Tanganyika railway) to Mwanza, on Vic- toria Nyanza; the northern from Nimule to Rejaf, along the banks of an unnavigable stretch of the Upper Nile.
These cross- Africa routes were valueless for through goods traffic ; their function was to bring the produce of Central Africa direct to the nearest seaport. Thus the Tanganyika railway made Dar es Salaam the natural outlet for the trade of a large portion of the eastern part of the Belgian Congo. With these mam routes may be mentioned the line (built 1916-8) from Qantara on the Suez Canal, across the Sinai peninsula to Gaza, which put Africa and Asia in direct railway communication, Cairo being linked with Jerusalem, Damascus, Aleppo, etc.
With regard to trans- Saharan railways, from Algeria to the Niger countries, surveys made in 1912-3 showed that there were routes presenting no engineering difficulties. From Msala, in the Algerian Sahara, the route is by Anhet, W. of the Ahaggar (Hoggar) massif to the Niger at Tosaye (Burem), some 200 m. below Timbuktu. What was regarded as the first section of the trans-Saharan was the line from Biskra to Tuggurt, opened in 1914. From Tuggurt to Tosaye by the route indicated is 1,470 miles. A line from Blida to Jelfa, on the way to Laghwat, was also built.
French projects to connect the Middle Niger with the ports of the Guinea Coast were hindered by the World War. The scheme was for railways from Dakar (Senegal), Konakry (French Guinea), Abidjan (Ivory Coast) and Kotonu (Dahomey) to be carried inland to the French Sudan (Upper Senegal and Niger colony), and there united by a transverse line. Political and economic considerations induced the French to neglect the Gambia river (as being British), the natural outlet for the French Sudan the Gambia is navigable from the ocean by vessels drawing 13 ft. up to 153 m. inland. Of the lines proposed, that from Thies (Dakar) to Kayes, on the Sene- gal, begun in 1907, has a length of 682 m., of which about 100 m. remained to be built in 1920. The French Guinea line from Kon- akry reached Kurussa (365 m.) in 1910 and Kankan, in the French Sudan, 411 m. from Konakry, in 1915. This led to much of the trade of the countries in the Niger bend going to Konakry. The Ivory Coast railway from Abidjan, traversing a dense forest region, reached Buake (193 m.) in 1913. No progress northward had been made by 1921. The Dahomey railway had reached Save (162 m.) in 1912. All four lines are of the French standard West-African gauge, namely one metre. Besides the railways the French built many hundreds of miles of metalled roads, on which motor services connecting with the Niger countries were established.
In British West Africa local lines and extensions, on differing gauges, were built during 1910-20; there was no unity of plan such as marked the French programme in West Africa. The bridging of the Niger at Jebba, completed 1914, gave the chief Nigerian rail- way, that from Lagos to Kano (704 m. long), an uninterrupted service. In 1913 a new railway was begun from Port Harcourt, at the mouth of the Bonny river. It was completed to the Udi coal- fields (151 m.) by May 1916. From Zaria, on the Lagos-Kano rail- way, a branch line, built across the tinfield area to Bukuru (143 m.), was completed in Dec. 1914. Surveys were made for an exten- sion of the Port Harcourt-Udi line northward across the Benue river and thence north-west to a point, Kaduna, on the Lagos- Kano line. The building of this extension, some 450 m. in length, was begun in 1921. Motor services are maintained in connexion with the railways, which are Government owned.
In Morocco the French, from 1912 onward, built narrow-gauge railways for military purposes. By 1920 these connected (l) Sallee with Fez, and (2) Ujda, on the Algerian frontier, with Taza, while the section Fez-Taza was under construction. From Rabat via Casablanca another line was built to Marrakesh. The river divid- ing Sallee and Rabat was not bridged, but a ferry service was insti- tuted. In 1918 the French Government decided to reconstruct the lines on the normal gauge. Up to 1921 no progress had been made on the Tangier-Fez railway. In North-East Africa the decade 1910-20 saw the completion of the railway from Jibuti to Addis Abbaba, the capital of Abyssinia.
The greatest mileage of railways built in the period under consid- eration was in South Africa (see SOUTH AFRICA). A line from Beira to the Zambezi (in construction 1920) gave Nyasaland direct access to the ocean. The Germans provided their South-West Africa Protectorate with an extensive system of railways. In Uganda the British built a short railway linking Jinja, on Victoria Nyanza, with
